Hydraulic tappet construction



June 17, 1941. QyQQRI-HES 2,246,330

HYDRAULIC TAPPET conswnucnou Filed March 14, 1940 lNVE R CHE-L. OR'H/ESATTORNEY Patented June 17, 1941 HYDRAULIC TAPPET CONSTRUCTION CarlVoorhies, Detroit, Mich., asslgnor to Eaton Manufacturing Company,Cleveland, Ohio, a

corporation Ohio Application March 14, 1940, Serial No. 323,869

4 Claims.

This invention relates generally to automatic compensating tappets ,foroperating valves oi! internal combustion engines, and more particularlyto the addition of means thereto which improve the operation ofhydraulic tappets of such character. The general type or tappet withwhich my invention is associated is shown in my prior issued Patent No.2,074,034.

The principal object of the present invention is the provision of filtermeans in a hydraulic tappet construction around or adjacent the liquidconduit therein; by means of which operating fluid is conducted from thefluid supply reservoir to the compression chamberoi the hydraulic taD-pet in an air-free, clean condition. a I

A further object of the invention is the provision of separate,apertured washer-like filter the tappet embodying this invention, shownpositioned between a cam and valve stem.

Fig. 2 is a perspective view of an air filter means removed from thetappet construction shown in Fig. 1.

For a more detailed explanation of the several component parts andactual operation of the type of hydraulic tappet to which this inventionis applied reference may be had to my above identified prior patent,Fig. '7, only so much of the operation thereof as is necessary to effecta complete understanding of the improved device is recited herein.

disks which may be positioned on a conduit tor liquids in a hydraulictappet as above described in amounts of selected number on future orexisting tappets now in service without any alterations in construction.

Various problems have been encountered in the application of this devicefor the automatic com.-

pensation or slack take up in valve gear of in-.

ternal combustion engines, one oi. which is the problem of providingadequate means for relieving and bleeding air or compressible gas fromthe hydraulic medium carried in the reservoir of the I I tappet, inorder that the trapped hydraulictcola umn upon which the plunger restswill be as nearly as possibleincompressible when the plung er is forcedagainst the valve stem. Another has been to provide sufficiently cleanhydraulic medium, whichis generally supplied from the sump or thelubricating system or the engine, in view of the serious consequences ofeven small particles of foreign matter in the hydraulic fluid findingtheir way into the close fits maintained between the accurately finishedand. relatively recipr cable parts of'the hydraulic mechanism. Accoringly, to this end, the present invention accomplishes among otherthings the objects of the invention above enumeratedand to. behereinatter described.

Other objects; features and advantages will become apparent from a studyof the drawing and v accompanying description forming a part 01' thisspecification and more particularly pointed out in the appended claims.

For the purpose of illustrating the genus of the invention a concreteembodiment of the invention is shown in the accompanying drawing, inwhich a Fig. 1 is a longitudinal cross-sectional view 0! The-numeral Irepresents the end of the stem of the conventional p ppet valve which isresiliently urged downwardly to its seat in the well known conventionalmanner (not shown). The numeral 2 indicates a conventional camshaft withthe cam 3 mounted thereon. The numeral 4 represents the usualconventional tappet guide sleeve provided in the cylinder block of theengine. The numeral 8 represents a mushroom type tappet of theconventional shape'provided with an enlarged cam contacting head I andan elongated tubular body 8. The body 8 shown is provided with a hollowbore 8 closed at the lower end and which provides a. reservoir for oilwhich is supplied through the side of the guide 4 by the supply pipe llconnected with the usual lubricating system. The body of the tappet 8 isalso provided with a circumferential groove ll into which oil suppliedby the pipe l0 flows. An oil inlet aperture V I2 is provided in thetappet body '8' leading thereinto from the groove H to the reservoir 9into which the oil flows. The bore in the upper part oi. the tappet body8 is enlarged and an abutment shoulder I3 is thereby provided at thelower end or the enlarged portion of the bore. Inserted in the enlargedportion of the bore is a cylinder sleeve member ll which comprises acylindrical member having an enlarged bore in its upper end and aseparate shouldered tubular extension I! pressed therein at its lowerend, which, when the member ll isinserted in the enlarged bore of thetappet body 8, extends below the oil inlet aperture I2 and deep downinto the oil reservoir 8 in the lower part of the tappet body.

Positioned in the cylinder sleeve 14 a solid plunger ll, which contactsthe valve stem I with its upper end. is reciprocably mounted and adaptedto be biased outwardly with respect to the separate cylinder by means ofa spring ll. Positioned in the lower end of the cylinder I4 is a ball I!seating against and covering the upper end of the opening through thetubular extension l5. surrounding the ball is a retaining cage member09, having an aperture 20 in its upper end, and press-fitted into thereduced bore of the cylinder l4 abutting the upper end of the tubularextension 15 to retain it in place and fix the amount of ball travel.

The operation of the device is as follows:

As the cam rotates and the tappet head rides upon the base circle of thecam, the tappet body moves downwardly in its guide under the influenceof the spring pressed valve stem l. Normally and in a rigid andnon-extensible type of tappet, the pressure of the valve stem againstthe end of the tappet would cease shortly before the tappet reached thebase circle of the cam, thus relieving substantially all the pressure ofthe valve upon the tappet, In the device disclosed, however, when thepressure of the valve stem ceases, the coil spring ll will urge theplunger i6 outwardly and maintain its contact with the valve stem. Thisoutward movement or the plunger it will reduce the pressure in the spacebetween the end of the plunger l6 and above and within the ball cagemember i9 and permit the ball I8 to rise from its seat, under therelatively greater pressure in the oil reservoir 9, and permit oil inthe reservoir to flow past the ball and fill the space between the endof the plunger i6 and top of the cage member l9. Then as the tappetmoves upwardly through rotation of the cam and with the ball in closedposition the oil in the chamber in the lower portion of the cylinder Mwill be trapped, thus providing an incompressible hydraulic column whichwill maintain the plunger in flrm contact with the valve stem I duringthe entire stroke of the tappet. The pressure of the plunger l6 againstthe trapped oil thereunder normally will cause a slight leakage of theoil outward around the sides of the plunger, and the oil-so eliminatedwill be replaced as the cycle of operation repeats and the pressure ofthe valve stem upon the plunger is relieved when the tappet rides uponthe base circle of the cam and permits the spring I! to force theplunger outwardly thus permitting the ball to rise' from its seat andadmit more oil into the space between the end of the plunger l6 andabove the ball cage member is, as previously described.

Since the oil supply for the hydraulic valve tappet 6 is generally takenfrom the lubricating system of the internal combustion engine with whichit is associated, it is apparent that care must be taken that only cleanhydraulic fluid will be supplied to the relatively close fits maintainedbetween associated movable parts of the hydraulic tappets in order thatforeign particles will not interfere with the smooth operation thereof.

Difllculty has also been experienced in preventing air or compressiblegas from working into the hydraulic column under the plunger l6 whichwill compress when pressure is exerted upon the plunger and therebyintroduce lost motion, It is essential that the hydraulic column beneaththe plunger be as incompressible and rigid as possible in order topermit accurate and dependable adjustment and timing of the valvemechanism. There is inevitably some air and gas entrained in the oilwhich is pumped into the reservoir 9 inrthe tappet and part of this willtroduced air or gas that does not readily separate from the fluid supplyand that forms an emulsion with the oil during the rapid reciproca tionand churning of the fluid in the tappet as the engine is running is thepart that is necessary to remove in order to secure the proper valvelift with the hydraulic valve tappet, as aforementioned.

In the present invention these didlculties, l. e. of foreign particlesand compressible gas in the hydraulic operating fluid, have been solvedby providing in the oil reservoir 9 one or more filters 2| which in thisinstance are washer-like disks with an axial aperture therethrough so asto be positioned on the upper end of the tubular extension 55 and belowthe oil inlet l2, of the tappet body. The filters 2| are composed ofwool felt, or other suitable filtering material, and have an outerperiphery of suflicient extent to extend transversely across the fulldiameter of the annular reservoir Q. With this construction andarrangement of parts assuming the hydraulic fluid entering the tappetbody contains some air it must all pass downward transversely throughthe entire filtering means before it is accessible to the entrance tothe lower end of theliquid conduit l5 and the check ball l8. Thus anyair rise to the top of the reservoir where it will find its way out tothe atmosphere between the walls of the separate cylinder M and thetappet body 8. However, the portion of the inbubbles, foreign particles,or compressible gas will be prevented from passing, so that the liquidwhich finally enters through the check ball [8 into the hydraulic columnunder theplunger I6 is practically incompressible.

Formal changes may be made in the specific embodiment of the inventiondescribed without departing from the spirit or substance of theinvention, the scope of which is commensurate with the following claims.

What I claim is:

1. A hydraulic valve tappet comprising, in combination, a tappet bodyhaving a longitudinal bore closed at its lower end and open at the upperend and having an oil passage in its side wall above the closed end, thelower part of said body including a liquid reservoir, a hydrauliccompensating mechanism reciprocably received in the open upper end ofsaid bore, a valve controlled passage adjacent one end of saidmechanism, conduit means communicating at one end with said passage andat its other end with the interior of the tappet body adjacent saidclosed end thereof, and one or more oil filtering means disposed aroundsaid conduit means between said oil passage in the tappet body wall andthe end of said conduit adjacent the closed end of said tappet body.

2. The combination ina hydraulic valve tappet, according to claim 1, inwhich said oil flltering means comprise preformed annular washerlikedisks of wool felt snugly fitted in the bore of said tappet body andsaid oil conduit extended therethrough.

3. A hydraulic valve tappet comprising, in combination, a tappetbodyhaving a 10L5itl1diI1B-l bore closed at its lower end and adapted toreceive a liquid, a hydraulic compensating mechanism including aseparate cylinder disposed in said bore, a tubular projection on thelower part of said cylinder and extending into the lower part of thebore in spaced relation to the wall thereof, valve means controlling thepassage of fluid through said projection, means for introducing liquidinto the lower part of the bore at a point above the lower end of saidtubular element, and filtering means disposed around said tubular mean 3element between the lower end thereof and and mun: mechanismreclproeclaly recelved in liquid inlet. the 'open upper end of saidbore, a valve con- 4.'A hydraulic valve tappet comment combination, atappet body havln: l longitudinal bore cloned at its lower end and openat the upper endlndhavlnaanoflmelnltlaldewall .nbove the closed end, thelower port 0'! Illd body including: llquld :eeervolr. e hydnullccontrolled me adjacent one end of said mechanllm, and fllterln: meansinterposed in said liq- 5 uld recervoir between the oil passagetherelnto aid said valve controlled passage.

' CARL VOORHIES;

